Embodiments of the subject matter disclosed herein generally relate to mechanisms for supporting a liner in a gas turbine combustor, and more particularly, to spring loaded liner support mechanisms.
In a conventional gas turbine engine, air is ingested by a compressor, compressed and delivered to a combustor. The compressed air is mixed with fuel in the combustor and the air-fuel mixture is burned yielding hot, pressurized combustion gases. The combustion gases are expanded in a turbine, including one or more turbine wheels. Expansion of the combustion gases drives the turbine into rotation, thus producing useful mechanical power. The mechanical power is partly used for driving the compressor. Additional mechanical power is available on a turbine output shaft, for driving a load, such as a rotating turbomachinery, an electric generator or the like. The combustion process may occur inside a combustor liner. In some known combustors, the combustor liner is supported and at least partly housed in a combustor casing. In some embodiments a single casing of annular shape houses a plurality of combustor liners. In other embodiments, each combustor liner is housed in a respective combustor casing. The combustor liner and the combustor casing are substantially coaxial.
The compressed air and fuel are input and mixed at a rear end of the combustor liner. The combustion gases are output through an aft end of the combustor liner. The aft end is downstream in the gas flow direction from the rear end. The combustion gases are delivered from the combustor liner towards the turbine, where they are expanded. A transition piece fluidly connects the combustor liner and the turbine. A hula seal is usually interposed between the aft end of the combustor liner and the transition piece, the arrangement being such as to accommodate displacements due to thermal expansion and vibration of the combustor components.
Heat and vibration from the combustion process, as well as other mechanical loads and stresses from the gas turbine, e.g. due to unbalance of the compressor and/or turbine rotor, shake, rattle and otherwise cause vibrations of the combustor liner and the other components of the gas turbine in the proximity of the combustor liner. Accordingly, the combustor liner should be mounted such as to withstand the heat, vibrations and loads imposed by the combustion and other forces.
Typically a liner support arrangement is mounted close to the rear end of the combustor liner, between the combustor liner and the combustor casing. A typical liner support arrangement includes three individual support elements disposed between the combustor liner and the combustor casing, around a section substantially perpendicular on the gas flow direction in the combustor. Each support element typically includes a liner stop, which is constrained to the combustor liner, and a casing stop, which is constrained to the combustor casing. Each liner stop co-acts with the respective casing stop to support the combustor liner. A spring arrangement is usually located between the casing stop and the liner stop.
As mentioned above, due to the combustion process, as well as to the rotary motion of compressor and turbine, the combustor liner is subjected to vibrations, which cause wear of the interfaces between the combustor casing and the combustor liner. In particular, support elements which connect the combustor liner to the combustor casing are subject to wear and must be frequently replaced.
Existing combustors are designed such that the combustor liner can easily be demounted from the combustor casing for repairing or replacement purposes, along with the liner stops and relevant springs. Combustor casings are subject to less frequent maintenance and replacement interventions. Nevertheless, if the casing stops are worn out, the combustor casing has to be removed and the casing stops must be disassembled and replaced before the combustor casing can be mounted on the gas turbine engine again.
Removal of the combustor casing is a long-lasting operation and causes the gas turbine engine to remain inoperative for relatively long periods of time.
Accordingly, it would be desirable to provide improved combustor liner support arrangements, which solve or alleviates one or more of the drawbacks of known arrangements.